The role of bladder wall thickness in the evaluation of detrusor underactivity. Development of a clinical nomogram

Aims: The aim of our study was to investigate noninvasive predictors for detrusor underactivity (DUA) in male patients with lower urinary tract symptoms (LUTS) and benign prostatic enlargement (BPE). Methods: A consecutive series of patients aged 45 years or older with non-neurogenic LUTS were prospectively enrolled. Patients underwent standard diagnostic assessment including International Prostatic Symptoms Score, uroflowmetry, urodynamic studies (cystometry and pressure-flow studies), transrectal ultrasound of the prostate, and ultrasound measurements of the bladder wall thickness (BWT). Logistic regression analysis was used to investigate predictors of DUA, defined as a bladder contractility index < 100 mm H2O. A nomogram was developed based on the multivariable logistic regression model. Results: Overall 448 patients with a mean age of 66 ± 11 years were enrolled. In a multivariable logistic age-adjusted regression model BWT (odds ratio [OR]: 0.50 per mm; 95% confidence interval [CI], 0.30-0-66; P =.001) and Qmax (OR: 0.75 per mL/s; 95% CI, 0.70-0.81; P =.001) were significant predictors for DUA. The nomogram based on the model presented good discrimination (area under the curve [AUC]: 0.82), good calibration (Hosmer-Lemeshow test, P >.05) and a net benefit in the range of probabilities between 10% and 80%. Conclusions: According to our results, BWT and Qmax can noninvasively predict the presence of DUA in patients with LUTS and BPE. Although our study should be confirmed in a larger prospective cohort, we present the first available nomogram for the prediction of DUA in patients with LUTS.